Prepare grill for indirect grilling on medium-high heat.
Combine mango jam, chives, vinegar, and sriracha, stirring until smooth. Reserve 1/4 C. mango mixture; set aside. Brush oil evenly over chicken. Sprinkle with salt and pepper.
Place chicken on grill rack over indirect heat. Brush chicken with about 2 T. remaining mango mixture. Close lid, grill 90 minutes or until thermometer inserted into meaty part of thigh registers 165, turning chicken and brushing with about 2 T. mango mixture every 20 minutes. Transfer chicken to a platter and drizzle with reserved 1/4 C. mango mixture.
Calories 326; Fat 10.4g; Protein 38.7g; Sodium 515mg